Question

A potentiometer is used for the comparison of e.m.f. of two cells $E _ { 1 }$ and $E _ { 2 }$. For cell $E _ { 1 }$ the no deflection point is obtained at 20$E _ { 2 }$ the no deflection point is obtained at 30. The ratio of their e.m.f.'s will be

• A. 2/3
• B. ½
• C. 1
• D. 2

Answer 1

Answer: (A)

2/3

Answer 2

Ratio will be equal to the ratio of no deflection lengths i.e. $\frac { E _ { 1 } } { E _ { 2 } } = \frac { l _ { 1 } } { l _ { 2 } } = \frac { 2 } { 3 }$